Allow to run the MCP server in a Docker container.

[pfrenssen]

Proposed fix for #39

This packages the application using the official Python docker image.

I tried it out by setting my Phorge URL in .env and using the following setup in Cursor's mcp.json:

{
  "mcpServers": {
    "conduit": {
      "url": "http://127.0.0.1:8000/sse",
      "headers": {
        "X-PHABRICATOR-TOKEN": "api-xxxxxxxxxxxxxxxxxxxxxxxxxxxx"
      }
    }
  }
}